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authorJakob Unterwurzacher2021-08-23 22:10:23 +0200
committerJakob Unterwurzacher2021-08-23 22:10:23 +0200
commit806334eacf2e50d712844761aca2b11014ec99df (patch)
tree5d531146e92f7770a02e03107afdcb2fcc7a0ab1 /internal
parentb12ad292d4dfef1c00567fe3def7e73461d3c217 (diff)
cryptocore: add NonceSize to AEADTypeEnum
Have the information in one centralized place, and access it from main as needed.
Diffstat (limited to 'internal')
-rw-r--r--internal/configfile/config_file.go15
-rw-r--r--internal/cryptocore/cryptocore.go55
-rw-r--r--internal/siv_aead/siv_aead.go9
3 files changed, 45 insertions, 34 deletions
diff --git a/internal/configfile/config_file.go b/internal/configfile/config_file.go
index dba6c47..c1f93af 100644
--- a/internal/configfile/config_file.go
+++ b/internal/configfile/config_file.go
@@ -325,3 +325,18 @@ func getKeyEncrypter(scryptHash []byte, useHKDF bool) *contentenc.ContentEnc {
ce := contentenc.New(cc, 4096, false)
return ce
}
+
+// ContentEncryption tells us which content encryption algorithm is selected
+func (cf *ConfFile) ContentEncryption() (algo cryptocore.AEADTypeEnum, err error) {
+ if err := cf.Validate(); err != nil {
+ return cryptocore.AEADTypeEnum{}, err
+ }
+ if cf.IsFeatureFlagSet(FlagXChaCha20Poly1305) {
+ return cryptocore.BackendXChaCha20Poly1305, nil
+ }
+ if cf.IsFeatureFlagSet(FlagAESSIV) {
+ return cryptocore.BackendAESSIV, nil
+ }
+ // If neither AES-SIV nor XChaCha are selected, we must be using AES-GCM
+ return cryptocore.BackendGoGCM, nil
+}
diff --git a/internal/cryptocore/cryptocore.go b/internal/cryptocore/cryptocore.go
index 3e6f5e8..8fb7936 100644
--- a/internal/cryptocore/cryptocore.go
+++ b/internal/cryptocore/cryptocore.go
@@ -6,7 +6,6 @@ import (
"crypto/aes"
"crypto/cipher"
"crypto/sha512"
- "fmt"
"log"
"runtime"
@@ -20,42 +19,34 @@ import (
)
const (
- // KeyLen is the cipher key length in bytes. 32 for AES-256.
+ // KeyLen is the cipher key length in bytes. All backends use 32 bytes.
KeyLen = 32
- // AuthTagLen is the length of a GCM auth tag in bytes.
+ // AuthTagLen is the length of a authentication tag in bytes.
+ // All backends use 16 bytes.
AuthTagLen = 16
)
// AEADTypeEnum indicates the type of AEAD backend in use.
-type AEADTypeEnum int
+type AEADTypeEnum struct {
+ Name string
+ NonceSize int
+}
-const (
- // BackendOpenSSL specifies the OpenSSL backend.
- // "AES-GCM-256-OpenSSL" in gocryptfs -speed.
- BackendOpenSSL AEADTypeEnum = 3
- // BackendGoGCM specifies the Go based GCM backend.
- // "AES-GCM-256-Go" in gocryptfs -speed.
- BackendGoGCM AEADTypeEnum = 4
- // BackendAESSIV specifies an AESSIV backend.
- // "AES-SIV-512-Go" in gocryptfs -speed.
- BackendAESSIV AEADTypeEnum = 5
- // BackendXChaCha20Poly1305 specifies XChaCha20-Poly1305-Go.
- // "XChaCha20-Poly1305-Go" in gocryptfs -speed.
- BackendXChaCha20Poly1305 AEADTypeEnum = 6
-)
+// BackendOpenSSL specifies the OpenSSL backend.
+// "AES-GCM-256-OpenSSL" in gocryptfs -speed.
+var BackendOpenSSL AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-OpenSSL", 16}
-func (a AEADTypeEnum) String() string {
- switch a {
- case BackendOpenSSL:
- return "BackendOpenSSL"
- case BackendGoGCM:
- return "BackendGoGCM"
- case BackendAESSIV:
- return "BackendAESSIV"
- default:
- return fmt.Sprintf("%d", a)
- }
-}
+// BackendGoGCM specifies the Go based GCM backend.
+// "AES-GCM-256-Go" in gocryptfs -speed.
+var BackendGoGCM AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-Go", 16}
+
+// BackendAESSIV specifies an AESSIV backend.
+// "AES-SIV-512-Go" in gocryptfs -speed.
+var BackendAESSIV AEADTypeEnum = AEADTypeEnum{"AES-SIV-512-Go", siv_aead.NonceSize}
+
+// BackendXChaCha20Poly1305 specifies XChaCha20-Poly1305-Go.
+// "XChaCha20-Poly1305-Go" in gocryptfs -speed.
+var BackendXChaCha20Poly1305 AEADTypeEnum = AEADTypeEnum{"XChaCha20-Poly1305-Go", chacha20poly1305.NonceSizeX}
// CryptoCore is the low level crypto implementation.
type CryptoCore struct {
@@ -174,7 +165,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
log.Panic(err)
}
} else {
- log.Panicf("unknown cipher backend %q", aeadType.String())
+ log.Panicf("unknown cipher backend %q", aeadType.Name)
}
if aeadCipher.NonceSize()*8 != IVBitLen {
@@ -203,7 +194,7 @@ type wiper interface {
func (c *CryptoCore) Wipe() {
be := c.AEADBackend
if be == BackendOpenSSL || be == BackendAESSIV {
- tlog.Debug.Printf("CryptoCore.Wipe: Wiping AEADBackend %d key", be)
+ tlog.Debug.Printf("CryptoCore.Wipe: Wiping AEADBackend %s key", be.Name)
// We don't use "x, ok :=" because we *want* to crash loudly if the
// type assertion fails.
w := c.AEADCipher.(wiper)
diff --git a/internal/siv_aead/siv_aead.go b/internal/siv_aead/siv_aead.go
index eabb5e2..482efd9 100644
--- a/internal/siv_aead/siv_aead.go
+++ b/internal/siv_aead/siv_aead.go
@@ -19,6 +19,11 @@ const (
// KeyLen is the required key length. The SIV algorithm supports other lengths,
// but we only support 64.
KeyLen = 64
+ // NonceSize is the required nonce/IV length.
+ // SIV supports any nonce size, but in gocryptfs we exclusively use 16.
+ NonceSize = 16
+ // Overhead is the number of bytes added for integrity checking
+ Overhead = 16
)
// New returns a new cipher.AEAD implementation.
@@ -42,11 +47,11 @@ func new2(keyIn []byte) cipher.AEAD {
func (s *sivAead) NonceSize() int {
// SIV supports any nonce size, but in gocryptfs we exclusively use 16.
- return 16
+ return NonceSize
}
func (s *sivAead) Overhead() int {
- return 16
+ return Overhead
}
// Seal encrypts "in" using "nonce" and "authData" and appends the result to "dst"